Method of making lead-in seals



Oct. 4, 1949. w, sc -r 2,483,940-

METHOD OF MAKING LEAD-IN SEALS Filed D60. 3, 1946 Inventor: Wiiliam J.Scoifit,

M 8% Y His Aot orr ey.

Patented Oct. 4, 194Q METHOD OF MAKING LEAD-1N SEALS William J. Scott,Rugby, England, assignor to General Electric Company, a corporation ofNew York Application December 3, 1946, Serial No. 713,672 In GreatBritain March 3, 1943 Section 1, Public Law .690, August 8, 1946 Patentexpires March 3, 1963 4 Claims.

My invention relates to a method of making improved lead-in sealconstructions which is particularly adapted for use in electricdischarge devices designed for ultra-high frequency operation.

In high frequency electric discharge devices it is desirable to providea section of concentric transmission line, sealed through the envelopeof the device to provide accessible high frequency terminals for thedevice. In accordance with an important aspect of my invention, Iprovide a method of making an improved structure having a stem press orpinch of the type commonly used in electric discharge devices havingglass envelopes.

It is an object of my invention to provide a method of making a new andimproved lead-in seal construction for high frequency electric dischargedevices.

It is a further object of my invention to provide a method of making animproved lead-in construction for electric discharge devices employing aconcentric transmission line section as the high frequency terminals ofthe device.

It is a still further object of my invention to provide an improvedmethod of manufacturing an electric discharge device having a concentrictransmission line sealed through the envelope.

My invention will be better understood by reference to the followingdescription taken in connection with the accompanying drawing and itsscope will be pointed out in the appended claims. In the drawing, Fig. lis an elevational view in section showing the components of a lead-inseal embodying my invention as they appear before the sealing operation;Fig. 2 is a sectional view taken along the line 2--2 of Fig. 1; Fig. 3is an elevational view corresponding to Fig. 1 and showing the partsafter the sealing operation is complete; Fig. 4 is a sectional viewtaken along the line 4-4 of Fig. 3; Fig. 5 is an elevation view of ahollow cylindrical conductor employed in a modification of my invention;Fig. 6 is a sectional view taken along the line 6-6 of Fig. 5; Figs. '7and 8 are sectional views illustrating modifications of my inventionemploying the conductor shown in Fig. 5; and Figs. 9 to 14 inclusive aresectional views illustrating three further modifications of myinvention.

Referring now to the drawing, I have shown in Fig. 1, an embodiment ofmy invention in which a concentric transmission line including an outerhollow conductor I is received within the opening 2 of a glass body 3which is of the type commonly employed for providing the stem press ofan electric discharge device. conductor 4 of the transmission line isreceived within the outer conductor I and sealed to it by a body ofglass 5 which may to advantage be a glass bead which is sealed to theconductor 4 prior to assembly with the conductor I. As shown in Figs. 2and 4 conventional lead-in conductors 6 may also be positioned in theopening 2. The various parts described and illustrated in Figs. 1 and 2are assembled in a suitable jig and the parts heated by any suitablemeans (not shown) in the region at which the pinch or press is to beformed. It will be noted that the flattened portion 1 of the glass body3 and the glass bead 5 have the same longitudinal location so that theseal between the hollow conductor I and the press, as well as the sealbetween the glass body 5 and the outer conductor I may be madesimultaneously. After the glass parts have been heated sufiiciently torender them plastic or semi-plastic, pressure is applied to form theseal as illustrated in Figs. 3 and 4. The pressure is sufficient toflatten the outer conductor 1 of the transmission line at the region ofthe press and to contract it into sealing engagement with the bead 5. Itis readily appreciated that the change in shape of the conductor fromcircular to noncircular efiects a reduction in the cross-sectional areasufiicient to bring the outer conductor into engagement with the glassbead.

I have found that it is desirable in many cases to provide for the flowof glass from the press to the area between the inner and the outerconductors of the transmission line in order to avoid the necessity ofreducing of the cross-sectional area of the outer conductor when makingthe seal. In Figs. 5 to 6 is illustrated an outer conductor 8 ofsuitable construction for this purpose. The conductor 8 may be formed ofsuitable material such as copper-coated steel, and shaped on a mandrelof generally cylindrical cross section. As shown in Fig. 6, the edges ofthe sheet material need not be joined. At the region where the conductoris to be received in the press, a pair of openings 9 are provided onopposite sides of the conductor. It is apparent from Figs. 7 and 8 that,as the glass is heated and pressure applied, sufficient glass of thepress flows through the openings 9 and joins with the glass bead 5. InFigs. '7 to 14 parts corresponding with the parts illustrated in Figs. 1to 4 inclusive are designated by the same reference numerals. In Figs. 9to 10 is illustrated a modification of my invention which is verysimilar to that shown in Figs. 7 and 8. In Figs. 9 and 10 the outer con-A central solid 3 ductor is not provided with additional openings 9 andthe gap ll between the adjacent edges of the sheet material forming theconductor is relied upon to permit the glass from the press 3 to joinwith the bead 5.

On Figs. 11 to 14, I have illustrated still further modifications of myinvention in which the passages for allowing the flow of glass into theinterior of the outer conductor are provided by making the outerconductor in two sections arranged in aligned and longitudinal spacedrelation. As illustrated in Fig. 11, the outer conductor is made up oftwo parts l2 and 13 joined together at adjacent ends by small solidconductors It which are welded at opposite ends to the hollow conductorsl2 and I3. When only two conductors M are employed, as illustrated inFigs. 11 and 12, it is possible to rely entirely on the flow of glassfrom the press body 3 and no bead on the inner conductor is required.

The modification shown in Figs. 13 and 14 is very similar to that shownin Figs. 11 and 12 except that four conductors I l are employed to jointhe hollow conductors l2 and i3 together. These conductors it arearranged within the conductors l2 and i3 and as illustrated a glass bead'5 is provided on the inner conductor 4. It will be appreciated that inthe modifications in Figs. 7 to 14 inclusive, the parts are assembled inthe desired relationship and held in position by a suitable jig whilethe parts are heated at the region where the press is to be formed untilthe glass is suificientiy plastic to fiow through the outer conductorupon the applications of pressure.

My invention as illustrated by the embodiments described above is welladopted for use in electric discharge devices utilizing a stem presswhich is in general of conventional design and which may be manufacturedwithout any additional press operations over that required for theseal-in of the conventional lead-in conductors.

While I have described and illustrated a particular embodiment of myinvention, it will be obvious to those skilled in the art that changesand modifications may be made without departing from my invention in itsbroader aspects, and I. therefore, aim in the appended claims to coverall such changes and modifications as fall within the true spirit andscope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. The method of sealing a concentric transmission line including innerand outer conductors through the press of an envelope for an electricaldischarge device comprising the steps of locating a lass bead on theinner conductor of the line, assembling the inner and outer lineconductors and the glass stem on which the press is to be formed in arequired relation such that the bead is located at the position of thepress, applying heat to render plastic the bead and the portion of thestem at which the press is to be formed, and then applying sufficientpressure to the heated portion of the stem to collapse that portion ontothe outer conductor and to distort the outer conductor so as to causethe bead completely to fill the outer conductor at the press.

2. The method of sealing a concentric transmission line including innerand outer conductors through an insulating body of an envelope for anelectrical discharge device comprising the steps of locating a glassbead on the inner conductor of the line, assembling the inner and outerline com ductors and the body of insulating material in a requiredrelation such that the bead is located at the position at which the sealbetween the outer conductor and the body is to be formed, the outerconductor having an opening therethrough at the region where it passesthrough said body, applying heat to render plastic the bead and therequired portion of the body, and then applying sufiicient pressure tothe heated portion of the body to cause the glass to flow through theopening to coalesce with the glass bead and embed the outer and innerconductors completely in the glass and form a vacuum-tight seal betweenthe conductors and between the outer conductor and said body.

3. The method of sealing a concentric transmission line including innerand outer conductors through a glass body forming a part of an envelopefor an electrical discharge device, said outer conductor having anopening therethrough com,- prising the steps of assembling the inner andout or line conductors and the glass body in a required relation suchthat the opening in the outer conductor is located at the point wherethe, seal to said body is to be formed, applying heat to render plasticthe required portion of the body and then applying sufiicient pressureto the heated portion of the body to collapse that portion onto theouter conductor and to cause a part of the glass to flow through theopening into the interior of the outer conductor to form a vacuum-tightseal between said outer conductor and said body.

4. The method of sealing a concentric transmission line including innerand outer conductors through the press of an envelope for an electricaldischarge device comprising the steps of locating a glass bead on theinner conductor of the line, assembling the inner and outer lineconductors and the glass stem on which the press is to be formed in arequired relation such that the bead is located atthe position of thepress, applying heat to render plastic the bead the portion of the stemat which. the press is to be formed and then applying sufiicientpressure to the heated portion of the stem to collapse that portion ontothe outer conductor and to affect a seal including said bead betweensaid inner and outer conductors.

WILLIAM J. SCOTT.

REFERENCES CITED The following references are of record in the file ofthis patent:

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1,271,245 Von Recklinghausen July 2, 1918 1,359,134 Wetmore Nov. 16,1920 1,456,110 Mackay May 22, 1923 1,489,099 Reynolds Apr. 1, 19241,680,738 Hull Aug. 14, 1928 2,030,185 Rose Feb. 11, 1936 2,057,305 LyleOct. 13, 1936 2,162,489 Matthieset al June 13, 1939 2,173,473 EdwardsSept. 19, 1939 2,190,302 Waldschmidt Feb. 13, 1940 2,197,511 ScharfnagelApr. 116, 1940 2,220,742 Thorson Nov. 5,, 1940 2,279,818 Freeman Apr.14, 1942 2,394,398 Mouromtseff, et a1. 1-- Feb. 5, 1946 2,414,785

Harrison etal Jan. 21, 1947

